Coupling nut



FIG. 1 is a perspective view of a coupling nut showing my new design;

FIG. 2 is a front elevational view showing the design for the coupling nut of FIG. 1;

FIG. 3 is a rear elevational view showing the design for the coupling nut of FIG. 1;

FIG. 4 is a left side elevational view showing the design for the coupling nut of FIG. 1;

FIG. 5 is a right side elevational view showing the design for the coupling nut of FIG. 1;

FIG. 6 is a top plan view showing the design for the coupling nut of FIG. 1; and,

FIG. 7 is a bottom plan view showing the design for the coupling nut of FIG. 1.

The broken lines shown in the drawings illustrate portions of the coupling nut that form no part of the claimed design. 

CLAIM The ornamental design for a coupling nut, as shown and described. 